Plesiosaurs are an extinct order of marine reptiles. They lived during the Mesozoic Era and were distributed in all of the world’s oceans. The earliest of this order developed at the end of the Triassic Period about 203 million years ago. They went extinct with the dinosaurs at the end of the Cretaceous Period about 65 million years ago. More than 100 species of Plesiosaur have been discovered around the world.

They had large torpedo shaped bodies, four flippers, and short tails. They were meat eating predators. They gave birth to live young. Some scientist believe they were warm blooded.

It is believed that the plesiosaurs descended from land reptiles that became adapted to life in the sea.

The name came from the Greek word plesios meaning near to and the latinized saurus meaning lizard.

Two Body Types
There were 2 main groups of plesiosaurs, a long necked variety had small heads. They ate fish and other small marine animals. It is believed that they were slow but agile swimmers. The other type had short necks and large heads. They were fast swimmers that were dominant predators that could catch and eat large prey.

As a whole plesiosaurs ranged from about 1.5 meters or 5 ft to about 15 meters or 49 ft. Kronosarus and Liopleurodon were the largest of this group.

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